Amplifying system



Oct. 17, 1933. v. D. LANDON 1,930,523

AMPLIFYING SYSTEM Filed May 17, 1928 INVENTOR if. 5 W

- ATTORNEY Mfr/7022 0 16214621.

Patented Oct. 17,1933

N T D S A S AT OF EE I .msosza AMPLIFYING srs'rE' Vernon D. Landon, EastPittsburgh, Pa., assignor to .Westinghouse Electric & ManufacturingCompany, a corporation of Pennsylvania Application May 17, 1928. SerialNo 278 ,593 9 Claims. ('01. 179-171) My invention relates to amplifyingsystems, andithas particular relation to amplifying systems of the typewherein a plurality of thermionicv devices are utilized for theamplification of high' frequencies, the said devices being interconnected through transformers.

By reason of the fact that commercial'radio work is now'being carried onover a .wide range of frequency-channels, a commercial radio receivermust of necessity be so constructed as to be responsive vtor'nany morefrequencies than the usualamateur, or broadcastreceiven'if the ,re-

ceiver is to be utilized in situationsfwhere it is not feasible tomaintain separate receivers for each of a plurality of frequency-bands;

A single tunable transformer, of :the typegenerally'used for intertubecoupling, is usually only efficient .over a relatively narrow band ofireof the tubes to the input circuits thereof throughtheqinter'electrode capacity, become very troublesome. It has previouslybeen proposed to neutralize the tendency toward self-oscillation 40, byfeeding back through a neutralizing circuit,

suflicient energy in opposite phase, to the unde-i sired feed-back tocancel the'latter.

Anti-oscillation systemsof many of the con-' ventional types give good,results over a somewhat limited tuning range, but necessitates constant.re-adjustment when plug-in coils or .transformers are used to cover a"wider range of frequencies. p i It is,*'.accordingly,- an object' .of myinvention to provide an amplifying system capable of eflicientlycoveringa much wider range ofcfrequericies than analogous systems constructedaccord-' ing to the teachings of the prior art.

'Another object of my invention is to provide an amplifying systemwherein any one of-a plusubstituting',,in the set, different groups:of-the ingall of 'the tuning elements thereof by means.

When a plurality, of thermionic devices are feeding back of energy fromthe output circuits rality of plug-in coils, or transformers, may be;utilized as an inter-tube coupling device without disturbingtheneutralization of the system against parasitic oscillations. e 1

Another ,object'of my invention is to provide a Q- plug-in transformerthat shall be particularly adapted for use'in an amplifying system of,the aforementioned type.

In accordance with myinvention, I providea rad-i0 receiving systemhaving,,as fixede1ements thereof, a plurality of variable condensers,each condenser being connected across the input -ter'-. minals of athermionic device, and I furtherpro vide means whereby all of saidcondensers may be simultaneously adjusted by a single actuating 0%device. I provide also "a plurality of intertube: transformers,eachtransformer being mounted on a base having asymmetrically arrangedplug terminals, Also, I mount one or more small variable neutralizingcondenserson the saidibase,;

and so arrange the permanent wiring of the receiving. set and theconnections of the"transe:

former to the neutralizing condenser, that, when the transformer isplugged into an appropriate" socket in the receiving set, the saidneutralizing 8.

condenser is properly connected in the circuit," as well as the primaryand secondary windings of. the transformer. h 1

The novel features that I consider character 'istic of my invention areset .forth with particu- 35 larity in the appended claims. The inventionitself; however, both as to its organization and its methodof operation,togetherwith further objects and advantages thereof, will best beunderstood from a'consideration of the, followingdescription of aspecificembodiment, taken 'i'n connection withthe accompanying drawing,in which.

Fig.v 1 is a-diagrammatic view of a portion of a composite amplifyingsystem comprising several embodiments of my invention, I

Fig. 2. is a perspective view of a plug-in transformer constructedaccording to my invention,.a portion of the insulating wire-supportingform being broken away to show the manner in which a neutralizingcondenserv is mounted in the interior thereof, Y i 1 Fig. 3 is a bottom.plan view of the deviceshown inFig.2,'-. I m

' Fig. 4 is an elevational view of the device Show "in Fig. -2, aportion thereof being sectionaliz'ed along aline correspondingtojtheline IV--IV of Fig. 3,and f Fig.- 5 is a perspective view showing themanner in which the openings in a socket device are so 1110 45 mediate.pointon the secondary winding is conarranged as to preclude incorrectpositioning therein of one of the plug-in transformers.

Fig. 1 illustrates what might well be termed a composite amplifyingsystem, in which two modifications of my invention are incorporated. Theapparatus shown therein comprises a plurality of thermionic amplifyingtubes 1 and 2 and a thermionic detector tube 3. Each of the tubes is ofthe usual type, having a filament 4, a grid 5, and a plate 6, and all ofthe tubes are supplied with plate potential from a common source 7. Acommon source 8 supplies potential to the filaments of the tubes, whichfilaments are connected in parallel to the source through a plurality ofconductors 10 and 11.

A pair of telephones 12, or an analogous device, is included in theoutput circuit of the detector tube 3. A plurality of plug-terminalreceiving elements 13, 14, 15, 16, 1'7 and 18 are associated with thefirst amplifying tube, being arranged as shown in Fig. 5, the elements15, 16 and 17 being conductively connected to the plate, the grid andthe filament, respectively- A variable condenser 20 constitutes a fixedcomponent of the amplifying system, the rotary plates thereof beingconnected to the plug-terminal receiving element 18, and the stationaryplates being connected to the grid of the tube and the element 16.

Aninput transformer, comprising a primary winding 21 and a secondarywinding 22, is associated with the first thermionic tube by means of theaforementioned plug-terminal receiving devices 13, 14, 15, 16, 1'7 and18. The transformer, which is shown in detail in Figs. 2, 3 and 4,comprises a cylindrical form 23 of insulating material,

on which are positioned the primary winding 21 and the secondary winding22. A cylindrical closure 24, or base-member, is semi-permanently fixedin .one end of the insulating form 23 and carries a plurality ofplug-terminals 25, 26, 27, 28,

30 and 31. The ends of the primary winding are conductively connected tothe terminals 25 and 26, the ends of the secondary winding are connectedtothe terminals 2'7 and 28, whilean interductively connected tothe'terminal 30.

A neutralizing condenser, comprising a fixed plate 32 and a movableplate 33, is mounted on the base-member 24, the movable plate beingadjustable toward and from the fixed plate by the rotation of a screw 34which extends through a saddle-shape element 35 arranged transversely ofthe condenser and held on the base-member by a plurality of bolts 36.Access may be had to the adjusting screw 34 by removing a closure 37which fits the end of the insulating form opposite to'the base-member,the said closure preventing, to some extent at least, the alteration ofthe condenser setting by dust or moisture.

The movable plate of the neutralizing condenser is connected to theterminal 23 and to one end of the secondary winding 22. The fixed plateof the neutralizing condenser is connected to a terminal 31 .to which noother part of the coupling device is:connected..

A. plurality of conductors 40 and 41 are connected to the fixedterminal-receiving elements 13 andr14,: respectively, which conductorsmay be included either in any energy-receptor circuit (not shown) orwhich maybe included in the output circuit of a preceding amplificationstage.

It 1 will, accordingly, be apparent that, when the coupling device isinserted in the socket-elements, the inductor 22. is thereby connectedin shunt'tothe tuningcondenser 20, and a reversed feed-back circuit iscompleted from the plate 6 of the device 1 to the filament 4 thereof,through the neutralizing condenser and that portion of the inductorcomprised between the lower end of the inductor and the connectiontherefrom to the filament. The circuit thus constituted is that known tothose skilled in the art as the Rice circuit.

The thermionic device 1 is illustrated as being coupled to thethermionic device 2 through an ordinary plug-in transformer, having aprimary winding 42 and a secondary winding 43, although a couplingdevice similar to that just described could be used in this position, ifdesired.

The thermionic device 2 is illustrated as being coupled to thethermionic device 3 through a plug-in device constructed according to amodification of my invention. The later device comprises a transformerhaving a primary winding 44, a part of which is included in the outputcircuit of the thermionic device 2 and a part of which is utilized forneutralizing the tendency of the system toward self-oscillation, and asecondary winding 45, which winding is included in the input circuit ofthe thermionic device 3. The transformer mounting also carries aneutralizing condenser 46 which serves to complete a neutralizingcircuit between the plate and filament of the device, as illustrated.

It lies. within the scope of my invention to utilize coupling devices ofboth of the types hereinbefore described, although, in any givenreceiver, it may be preferable to couple all of the thermionic tubescarrying high frequencies through devices of the same type.

It also lies within the scope of my invention to utilize eitherauto-transformers or tuned impedances as. coupling devices betweenthermionic tubes,.instead of the transformers illustrated.

When practicing my invention, the neutralizing condensers carried byeach of the plurality of coupling devices necessary to cover a range ofcommercial frequencies are carefully preadjusted while the said devicesare in position in the receiving set with which they are later to beused. 120 When, subsequent to the initial adjustment, it is desired toshift from one frequency-range to another, one group of coupling devicesmay be removed and another substituted therefor with full assurance thatthe neutralization of the set will 125 not be disturbed in theslightest.

When the thermionic tubes with which the coupling devices are adjustedare replaced by others, the neutralization of the set is substantiallyunaffected, inasmuch as the tube capacity is, in general, only a smallpercentage of the total distributed capacity of the inductors comprisedin the coupling device.

My invention, therefore, proves of very marked advantage in thecommercial reception of radio signals, in situations, such as onship-board, where it is not feasible to operate a plurality of receivingsets, and where it is often necessary to rapidly shift from onefrequency-range to another. 1

Although I have shown only two specific forms of my invention, it isdeemed sufiiciently broad in scope to cover all coupling devices forhighfrequency amplifying systems, and other amplifying systems, whereina neutralizing condenser is a constituent part thereof and insertabletherewith into a socket-device. My invention, therefore, is notto belimited except insofar as is necessitated by the prior art or by thespirit of the appended claims.

I claim as my invention: v I r 1. .As an article of manufacture, acoupling device comprising a plurality of inductorsfa supporting elementfor holding said inductors in inductive relation, a base-member in whichsaid element is mounted and a neutralizing condenser mounted on saidbase-member.

,2. As an article of manufacture, a coupling":

device comprising a transformer, a base-member on which said transformeris mounted, plug-terminals on said base member, a neutralizing-condenser mounted on said base-member and connections between saidtransformer, said condenser, and said plug-terminals.

3. In combination, radiofreceiving, apparatus comprising at leasttwoth'ermionic tubes, a socket device, a coupling device comprising aninductor and a neutralizing condenser, the capacity of which isapproximately the-capacity between two electrodes of a receiving tube,plug-terminals carried by said'coupling device, connections between saidthermionic tubes and said socket 'deviceand connections between saidinductor, said plugterminals and said neutralizingcondenser, wherebywhen said terminals are properly inserted in said'socket device, acircuit is completed for the,

transfer of energy between said thermionic devices throughsa'idiinductor and said neutralizing condenser. v V

4. In combination; radio receiving apparatus comprising at least twothermionic tubes, a socket device therein, connections from 'said tubesto said socket device,a coupling device comprising an inductor and aneutralizing condenser,-plugterminals carried by said coupling deviceand connections between said inductor, said plugterminals and saidneutralizing condenser, whereby, when said terminals. arep'roperlyinserted in said socket device, a circuit is completedfor thetransfer of energy from bneof. said thermionic tubes to the other ofsaidtubes through said in.-

tially preventing dust andf'dampness from in- 37 ductor and anothercircuit is completed through i said neutralizing, condenserforpreventing the generation of parasitic oscillations. v

-: 5. As an article of manufacture, a coupling device comprising aninductor, an insulating form for said inductor, a base'for supportingsaid form,

a neutralizing condenser mounted on said base interiorly of said formand means for substanjuriously'afiecting said condenser. 6. As anarticle of manufacture, a coupling device comprising an inductor, aninsulating hol- I low formfor said inductor, semi-permanent cloformfor-said inductor, semi-permanent closures for the ends of said form,and an adjustableneuf tralizing condenser mounted on'one of saidclosures interiorly of said form, the other of'said'; closures beingremovable to permit the adjustment of said condenser. 8. As an articleof manufacture, a coupling de- [vice comprising an inductor and aneutralizing condenser supported within said'inductor, the capacity ofsaid neutralizing condenser being approximately the capacity between twoelectrodes of a receiving tube. I I

r 9,1 As an article of manufacture, a coupling device comprising aplurality offinductors and a neutralizing condenser, the capacity ofwhich is 0 approximately the capacity between two elec-,

trodes of a receiving tube and a common support for both said inductorsand said neutralizingcondenser.

VERNON D. LANDON. 115'

